Talipes equinovarus (clubfoot) means a disorder of a walking function, which causes stumbling easily by stubbing a toe against the ground during walking. This is because inward bending of a foot directs its sole inward, and impossibility of controlling an ankle causes a tiptoe side of the foot (referred to toe, hereinafter) to droop downward.
In order to prevent the stumbling during walking, a toe is corrected upward generally to prevent the drooping downward of the toe. Various types of body orthoses have been proposed for the purpose of correction. As shown in FIG. 5C, a state of a foot positioned parallel to a horizontal direction orthogonal to a leg of a posture parallel to a vertical direction (indicated by a solid line) is set as a normal state. A case of lifting the foot around a malleolus (not shown) from the normal state as indicated by a virtual line (chain double-dashed line) is called dorsiflexion, while a case of lowering the foot from the normal state is called plantar flexion.
In the conventional body orthosis, for example, against an upper body protective members adjacent to each other in upper and lower directions, a lower body protective member is rotatably constructed. The lower body protective member is set to be rotatable only within a predetermined angle (e.g., 45°) to the dorsiflexion side from the normal state. Thus, dorsiflexion is carried out while plantar flexion from the normal state is prevented.
In the case of walking on a flat land by using the conventional body orthosis, a leg is slightly inclined forward immediately before the leg of a healthy side is stepped forward to lift a foot of the body protective member side (see FIG. 7B). Thus, simultaneously with the lifting of the foot, the lower body protective member rotated to the dorsiflexion side is returned to the normal state by weight of the foot, making it possible to reduce stumbling more compared with the case of the drooped toe. However, in walking on a downward slope, the body protective member of the foot side (lower side) need to be rotated to the plantar flexion side against the body protective member of the leg side (upper side). With the above-described constitution, however, plantar flexion cannot be carried out, resulting in unstable walking of a forward-inclined posture. Thus, walking of a near natural state becomes difficult. Moreover, in walking on an upward slope, by landing the foot, the lower body protective member loading and supporting the foot can be subjected to dorsiflexion. However, when the foot in the state of dorsiflexion was lifted, the lower body protective member was returned to a horizontal posture by the weight of the foot, causing the toe to touch the slope and stumble. Moreover, by changing the constitution to one having a rotational angle for enabling plantar flexion on the downward slope, walking can be carried out on the downward slope. However, walking from the downward slope to the flat land or the upward slope is impossible with this constitution. Thus, it has been extremely difficult to handle the body orthosis.